1. Field of the Invention
This invention relates to a luminous key top whose display sections shine in a dark environment, e.g., at night.
2. Description of the Related Art
Luminous key tops having display sections emitting light are being used in various fields, for example, on operating knobs in vehicle equipment. Recently, there is a demand for a plurality of multi-colored display sections in a single key top.
FIG. 4 is a sectional view showing a conventional example of such a multi-colored luminous key top. The reference numeral 1 indicates a display member formed of a transparent or a translucent synthetic resin. The reference numeral 2 indicates a light-transmitting color layer covering the surface of the display member 1. The color of this light-transmitting color layer 2 may, for example, be white. The reference numeral 3 indicates a shielding color layer which is deposited on the light-transmitting paint 2 by painting, sputtering, evaporation, etc. The color of this shielding color layer 3 may, for example, be black. This shielding color layer 3 is partly removed by applying a laser beam thereto. The resulting exposed portions of the light-transmitting color layer 2 constitute a plurality of display sections 4, 5 and 6. The reference numerals 7, 8 and 9 indicate colored transparent films attached to the under surface of the display member 1 in correspondence with the display sections 4, 5 and 6. These transparent films 7, 8 and 9 may be of different colors, for example, red, blue and yellow.
This conventional luminous key top, constructed as described above, functions as follows: When in a bright environment, as in daytime, the plurality of display sections 4, 5 and 6 are visually recognized as such due to the difference in color between the shielding color layer 3 and the light-transmitting color layer 2. External light such as sunlight is utilized in this case. When in a dark environment, e.g., at night or in a tunnel, a light source 10, such as a lamp, provided within the key top is lighted up. Part of the light from this light source is transmitted through the display member 1 and the light-transmitting color layer 2 and is partly shielded by the shielding color layer 3, thereby enabling the image formed in the display sections 4, 5 and 6 to be seen in a dark place as luminous displays emitting light in red, blue and yellow.
The conventional luminous key top described above, however, requires the attachment of several types of colored transparent films to the under surface of the display member corresponding to the respective display sections. This involves poor productivity and high cost. Furthermore, when the display sections are arranged close to each other, the light transmitted through one of the colored transparent films is likely to interfere with the light transmitted through the adjacent film, resulting in the mottling of the illuminated colors.